[4 weeks' administration of omeprazole: effect on acid behavior and basal hormone levels]

We have assessed the effect of omeprazole (30 mg daily) on gastric acid secretion as well as on basal hormone levels (fasting gastrin; TSH, T3, T4, TBG; insulin, glucagon, C-peptide; prolactin, testosterone, 17-beta-oestradiol, dihydroepiandrosterone, cortisol and PTH) in 8 healthy volunteers before and after a 28 day treatment. On day 29, i. e. one day after the last omeprazole dose, mean stimulated acid output was still reduced from 27.4 +/- 3.5 mmol H+/h (+/- SEM) to 7.8 +/- 1.4 mmol H+/h (72% inhibition). Fasting gastrin levels were raised from 55.5 +/- 6.8 pg/ml to 80.9 +/- 6.7 pg/ml (33% increase). On day 39, stimulated gastric acid secretion and fasting gastrin levels have been returned to pretreatment values. Basal levels of prolactin, testosterone, TSH, T3, T4, TBG, cortisol, PTH, 17-beta-oestradiol, insulin, glucagon, c-peptide, dihydroepiandrosterone remained unchanged by a 28-day omeprazole treatment. Omeprazole is a highly effective antisecretory compound without any effect on the basal hormone levels tested. Even after 28 days its effect on acid secretion and fasting gastrin levels was fully reversible.